Not very efficient at that scale, I'm told. At you move to larger scale and longer periods of storage, other solutions surpass batteries.
Sent from my iPhone > On May 4, 2015, at 10:20 AM, robert winfield via EV <ev@lists.evdl.org> wrote: > > > dont forget aggregating, say, 1,000 of these 10kW Powerwalls into a 10 > megawatt virtual power plant VPP, (or any multiplier) for microgrids of > distributated generation > -------------------------------------------- > On Fri, 5/1/15, Robert Bruninga via EV <ev@lists.evdl.org> wrote: > > Subject: Re: [EVDL] Tesla plugs into new market with home battery system > (backup foolishness) > To: "Electric Vehicle Discussion List" <ev@lists.evdl.org> > Date: Friday, May 1, 2015, 9:39 PM > > Huh? Plenty wrong with > your assumptions. > >> $6k > of golf cart batteries is about 60 of them; that's > around 80 KWH of > storage! Who on earth needs > that much for a home. > > My > solar panels produce typically 60 to 70 kWH every sunny > day. If I do > not use every bit of it every > day, then I am wasting my solar investment > right? Hence, I sell it to the grid every > day and buy it back when I > need it at no net > cost.. > > If I had to store it > in batteries (at your proposed 10% daily depth of > discharge) then I would need 600 kWh of > batteries or $60K investment (and > replace it > every 10 years). Again, batteries MAKE NO ECONOMICAL > SENSE > WHATSOEVER compared to grid-tie. > BUT... > > BUT, if utilities > began paying the homeowner the same TEN-TIMES PEAK rates > they have to pay for power during summer peaks, > then of course, batteries > coiuld make some > economical sense. They don't have to handle the > full > working load of my solar array, but > only enough to meet those > instantaneoud peak > value periods... > > Bob > > > > -----Original Message----- > From: EV [mailto:ev-boun...@lists.evdl.org] > On Behalf Of Lee Hart via EV > Sent: Friday, > May 01, 2015 7:02 PM > To: Electric Vehicle > Discussion List > Subject: Re: [EVDL] Tesla > plugs into new market with home battery system > (backup foolishness) > > Robert Bruninga via EV wrote: >>> A quality GC2 golf cart battery > (Trojan, US Battery, etc.) is 220-240 >>> amphours at the 20-hour rate, and > costs $75-$150. They are good for > 5-10 years, and 600-1200 discharges to 50% or so state of > charge. >> >> No, not > BOTH. One or the other. 5-10 years just sitting there > doing >> nothing but waiting for the grid > to go out (4 hours a year around > here)... > > Correct. They are "used > up" once they have accumulated 600-1200 cycles, > *or* are 5-10 years old. > >> OR they barely will last 2 years in daily > solar-off-grid use (and >> note, you are > only getting 50% of their capacity just to last that > long)... > > That > would be the case if you discharge them 50% or so every day. > But 50% > is an excessively deep discharge if > you're going to use them every day. > > For daily use, you would limit your depth of > discharge to just 10% or so. > Then they would > still last for their calendary life; 5-10 years. > > Note that life is a function > of depth of discharge for *all* types of > batteries. If you expect them to last, the > shallower the discharge, the > better. > You'd also murder a lithium pack in a few years, if you > deeply > discharged it every day. > > If you really have a situation > that requires daily deep discharges, you > probably have to use the old Edison nickel-iron > cells. Aside from quality > or abuse, they are > the only type with an indefinite cycle life. > (There are 100-year-old Edison cells still in > use). > >> Yes, may as well > just throw $6k in the trash every few years since you >> never use them. The cost of the > electricity for the 4 hours average > outage per year is only about 80 cents. (1 kW for 4 > hours). Amazing >> how many people will > spend $6k for that 80 cent problem. > > I see a pretty heavy thumb on the scale here, > Bob. :-) $6k of golf cart > batteries is about > 60 of them; that's around 80 KWH of storage! Who on > earth needs that much for a home. > > You have to select the size > and type of battery according to the > application. Some will be best served with > lead-acid, some nickel-iron, > others lithium > etc. Some applications aren't appropriate for batteries > of > any type. > > If all you have to cover is 4 hours of outage > per year, then dumb old > lead-acids are going > to be the cheapest by far. Like I said, they will die > of old age before you wear them out. > > -- > Don't > worry about people stealing your ideas. If your ideas are > any good, > you'll have to ram them down > people's throats. -- Howard Aiken > -- > Lee Hart, 814 8th Ave N, Sartell MN 56377, > www.sunrise-ev.com > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use > NEDRA > (http://groups.yahoo.com/group/NEDRA) > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA > (http://groups.yahoo.com/group/NEDRA) > > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA > (http://groups.yahoo.com/group/NEDRA) > > _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
